MONTREAL -- Felix Auger-Aliassime has reached his first Grand Slam semifinal at the U.S. Open after 18-year-old Carlos Alcaraz stopped playing in the second set shortly after a visit from the trainer.
It was not immediately clear why Alcaraz retired from the match.
Auger-Aliassime was leading 6-3, 3-1 and called it "a weird ending."
He is a 21-year-old from Canada who is coached by Toni Nadal, Rafael's uncle.
Auger-Aliassime will face No. 2 seed Daniil Medvedev for a berth in the final.
This is a developing story that will be updated.
